Django 1.4+ provides its own middleware and setting to set the
X-Frame-Options header; you can use either this or Django’s, there’s no
value in using both.

Clickjacking attacks use layered frames to mislead users into clicking on a
different link from the one they think they are clicking on. Fortunately, newer
browsers support an X-Frame-Options header that allows you to limit or
prevent the display of your pages within a frame. Valid options are “DENY” or
“SAMEORIGIN” - the former prevents all framing of your site, and the latter
allows only sites within the same domain to frame.

Unless you have a need for frames, your best bet is to set “X-Frame-Options:
DENY” – and this is what SecurityMiddleware will do for all responses, if
the SECURE_FRAME_DENY setting is True.

If you have a few pages that should be frame-able, you can set the
“X-Frame-Options” header on the response to “SAMEORIGIN” in the view;
SecurityMiddleware will not override an already-present “X-Frame-Options”
header. If you don’t want the “X-Frame-Options” header on this view’s response
at all, decorate the view with the frame_deny_exempt decorator:

For sites that should only be accessed over HTTPS, you can instruct newer
browsers to refuse to connect to your domain name via an insecure connection
(for a given period of time) by setting the “Strict-Transport-Security”
header. This reduces your exposure to some SSL-stripping man-in-the-middle
(MITM) attacks.

SecurityMiddleware will set this header for you on all HTTPS responses if
you set the SECURE_HSTS_SECONDS setting to a nonzero integer value.

Additionally, if you set the SECURE_HSTS_INCLUDE_SUBDOMAINS setting to
True, SecurityMiddleware will add the includeSubDomains tag to the
Strict-Transport-Security header. This is recommended, otherwise your site
may still be vulnerable via an insecure connection to a subdomain.

Warning

The HSTS policy applies to your entire domain, not just the URL of the
response that you set the header on. Therefore, you should only use it if
your entire domain is served via HTTPS only.

Warning

Browsers properly respecting the HSTS header will refuse to allow users to
bypass warnings and connect to a site with an expired, self-signed, or
otherwise invalid SSL certificate. If you use HSTS, make sure your
certificates are in good shape and stay that way!

Note

If you are deployed behind a load-balancer or reverse-proxy server, and the
Strict-Transport-Security header is not being added to your responses, it
may be because Django doesn’t realize when it’s on a secure connection; you
may need to set the SECURE_PROXY_SSL_HEADER setting.

Some browsers will try to guess the content types of the assets that they
fetch, overriding the Content-Type header. While this can help display
sites with improperly configured servers, it can also pose a security
risk.

If your site serves user-uploaded files, a malicious user could upload a
specially-crafted file that would be interpreted as HTML or Javascript by
the browser when you expected it to be something harmless.

To learn more about this header and how the browser treats it, you can
read about it on the IE Security Blog.

To prevent the browser from guessing the content type, and force it to
always use the type provided in the Content-Type header, you can pass
the X-Content-Type-Options:nosniff header. SecurityMiddleware will
do this for all responses if the SECURE_CONTENT_TYPE_NOSNIFF setting
is True.

Some browsers have to ability to block content that appears to be an XSS
attack. They work by looking for Javascript content in the GET or POST
parameters of a page. If the Javascript is replayed in the server’s
response the page is blocked from rendering and a error page is shown
instead.

To enable the XSS filter in the browser, and force it to always block
suspected XSS attacks, you can pass the X-XSS-Protection:1;mode=block
header. SecurityMiddleware will do this for all responses if the
SECURE_BROWSER_XSS_FILTER setting is True.

Warning

The XSS filter does not prevent XSS attacks on your site, and you
should ensure that you are taking all other possible mesaures to
prevent XSS attacks. The most obvious of these is validating and
sanitizing all input.

If your site offers both HTTP and HTTPS connections, most users will end up
with an unsecured connection by default. For best security, you should redirect
all HTTP connections to HTTPS.

If you set the SECURE_SSL_REDIRECT setting to True,
SecurityMiddleware will permanently (HTTP 301) redirect all HTTP
connections to HTTPS.

Note

For performance reasons, it’s preferable to do these redirects outside of
Django, in a front-end loadbalancer or reverse-proxy server such as
nginx. In some deployment situations this isn’t an option -
SECURE_SSL_REDIRECT is intended for those cases.

If the SECURE_SSL_HOST setting has a value, all redirects will be sent
to that host instead of the originally-requested host.

If there are a few pages on your site that should be available over HTTP, and
not redirected to HTTPS, you can list regular expressions to match those URLs
in the SECURE_REDIRECT_EXEMPT setting.

Note

If you are deployed behind a load-balancer or reverse-proxy server, and
Django can’t seem to tell when a request actually is already secure, you
may need to set the SECURE_PROXY_SSL_HEADER setting.

In some deployment scenarios, Django’s request.is_secure() method returns
False even on requests that are actually secure, because the HTTPS
connection is made to a front-end loadbalancer or reverse-proxy, and the
internal proxied connection that Django sees is not HTTPS. Usually in these
cases the proxy server provides an alternative header to indicate the secured
external connection.

If this is your situation, you can set the SECURE_PROXY_SSL_HEADER
setting to a tuple of (“header”, “value”); if “header” is set to “value” in
request.META, django-secure will tell Django to consider it a secure
request (in other words, request.is_secure() will return True for this
request). The “header” should be specified in the format it would be found in
request.META (e.g. “HTTP_X_FORWARDED_PROTOCOL”, not
“X-Forwarded-Protocol”). For example:

SECURE_PROXY_SSL_HEADER=("HTTP_X_FORWARDED_PROTOCOL","https")

Warning

If you set this to a header that your proxy allows through from the request
unmodified (i.e. a header that can be spoofed), you are allowing an attacker
to pretend that any request is secure, even if it is not. Make sure you only
use a header that your proxy sets unconditionally, overriding any value from
the request.